Compound telephone.



No. 841,399. PATENTED JANI15, 1907.

0. G. F. HOLMGRENJSZ A. E. BRAHM.

COMPOUND TELEPHONE. APPLICATION FILED'AUG.24.19j96.

UNITED STATES PATENT orrion.

CARL GUSTAF FERDINAND HOLMGREN AND AUGUST EMANUEL BRAI-IM,

OF STOGKHOLM, SWVEDEN, ASSIGNORS TO AKTIEBOLAGET L. M. ERICS- SON 8: (10., OF STOCKHOLM, SWEDEN.

COMPOUND TELEPHONE.

Specification of Letters Patent.

Patented Jan. 15, 1907.

[implication filed August 24, 1906. Serial No; 331.936.

T0 at w/w'm, it may concern:

Be it known that we, CARL GUSTAF FERDI- NAND HoLMeREN and AUGUST EMANUEL BRAHM, subjects of the King of Sweden, and residents of Stockholm, Sweden, have invented new and useful Improvements in Compound Telephones, of which the following is a specification, reference being had to the accompanying drawings, which form a part of this specification.

The invention relates to improvements in compound telephones comprising a receiver and a transmitter or microphone connected by a handle-bar.

The object of the invention is to make the microphone more hygienic than heretofore without making any essential alterations of the usual construction in which the diaphragm of the microphone while the tele phone is used is in a vertical position and without reducing the capacity of the apparatus to be used for long distances.

The invention consists chiefly in the combination, with a telephone of the said kind, of an imperforate cover in front of the diaphragm of the microphone and a flange extending from said cover beyond openings provided in the side wall of the chamber between the said diaphragm and cover. The said flange will prevent saliva and other impurities from entering into the micro hone, the sound-waves at first striking on y the outer surfaces of the microphone-casing, which may be polished and of such shape that they may be easily wiped and kept clean. The said openings through which the soundwaves enter the microphone may suitably be provided only on the side facing the receiver and may be in the shape of slots or the like.

In the accompanying drawings we have shown one embodiment of our invention.

Figure 1 shows a side elevation and partial section of a compound telephone; and Fig. 2 shows a front elevation thereof, partly in section, on line II II in Fig. 1.

Referring to the drawings, the microphonecasing 6 has instead of the usual mouthpiece a metal cover 1, the thickness of the walls of which is chosen only with respect to the solidity and which thus is not adapted to let through in any essential degree the sound waves. The said cover consequently may not be compared with hygienic diaphragms of thin metal sheet or thin parchment or the like, which have been proposed as protecting device for the opening of the mouthpiece of the usual microtelephonic apparatus and which are adapted to let through the sound as fully as possible. In order that the soundwaves may enter the space or chamber 2 in front of the diaphragm 3 openings 4 are provided in the side wall of the cover 1. The said openings may, as mentioned above, preferably be provided only on the side facing the receiver 7, so that the Sound-waves coming from above cannot pass directly through the said space or chamber 2. In order to prevent saliva or the like from entering through the said openings 4, a flange 5 is provided around the upper or outer edge of the cover 1, the said flange extending beyond the openings 4 at some distance from the side wall of the cover, so that the said openings are fully covered by the flange 5.

The openings 4 suitably have the shape of slots, as shown in the drawings, but may also be of any other convenient shape, if desired.

The invention may easily be applied to the usual compound telephones by substituting for the microphone-cover having the usual mouthpiece a cover constructed in accordance with our present invention.

It may be understood that the invention may be varied in details without departing from the principle of the invention.

Having now described our invention, what we claim as new, and desire to secure by Letters Patent, is

1. The combination with a compound telephone com rising a receiver, a microphone, and a han e-bar connecting the receiver and the microphone, of an imperforate cover in front of the diaphragm of the microphone, and a flange extending from the Said cover beyond openings provided in the side walls of the chamber between the coverand the diaphragm of the microphone, substantially as and for the purpose set forth.

2. The combination with a compound tele phone com rising a receiver, a microphone, and a hand e-bar connecting the receiver and the microphone, of an imperforate cover on the microphone-casing having openings in its side walls, the said openings being located in front of the diaphragm of the microphone, and a flange extending from the outer edge of the cover beyond the said openings and at a distance from the side walls of the cover, substantially as and for the purpose set forth.

3. The combination with a compound telephone comprising a receiver, a microphone, and a handlebar connecting the receiver and the microphone, of an imperforate cover on the microphone-casing having openings in the portion of its side walls that faces the receiver, the other portion of the said side Walls being imperforate, and a flange extending from the outer edge of the cover beyond the said openings and at a distance from the. side walls of the cover, substantially as and, for the purpose set forth. 5

In testimony that we claim the foregoing 1 as our invention we have signed our names 1 in presence of two subscribing Witnesses.

CARL GUSTAF FERDINAND HOLMG-REN. AUGUST EMANUEL BRAHM.

Witnesses:

JOHN DELMAR, EWALD DELMAR. 

